Although the received view of Ernst Mach comported well with Mach’s historical influence on members of the Vienna Circle , it is inadequate, and it is now giving way to a more realistic and nuanced ‘neutral monist’ view. I defend the neutral monist tradition and show that it is actually a form of scientific realism, not positivism. I also argue that it is more in line with Mach’s contemporary reception, and that it leads to the views of American Realists, as well as to the views of our contemporary neutral monists. I start with a characterisation of some tenets of neutral monism in general, many of which were shared by William James and Bertrand Russell, both deeply influenced by Mach. I then detail the evidence for these views in Mach’s texts (including his notebooks and other documents). Seeing Mach as a kind of realist also casts much light on his scientific views and corrects a number of historical misconceptions regarding both atomism and Mach’s philosophy of space and time. Finally, I discuss Mach’s place in the neutral monist movement of James, Russell, and the American Realists, and the revival of these views in recent philosophy of mind.

Ernst Mach’s works have often been interpreted as presenting some version of idealism, such as phenomenalism. However, Erik C. Banks’ recent case for the rival neutral monist reading seems persuasive. But it still leaves a problem: how to explain why so many intelligent and thoughtful readers, some of them sympathetic to Mach, thought of him instead as some kind of idealist. I set out the major factors which tempt people into reading Mach thus and assess the strengths and weaknesses of these two readings.